It was a wet evening in May. We were driving into Boston from New Hampshire without definite plans on where to stay for the night. Suddenly a large motorway road sign loomed out of the mist: Route 9 West—Framingham. “I know that name,” I said, “Let's stay there: it would be interesting to see what sort of people are in the Framingham study, and what they eat.” So my wife and daughter agreed with my idea, for once.

It took some time, on a series of interconnecting highways, …

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